SF/Horror anthology. This series was one of eight SF anthologies launched or revived in an eight-month period (cover dates October 1955–June 1956), increasing Atlas's SF line from eight to sixteen books. This book, along with Strange Tales (Marvel, 1951 series), was one of only two SF anthologies to resume publication immediately following the publication hiatus caused by the collapse of Atlas's distributor and the subsequent restructuring known as the "Atlas Implosion".

Scripts were generally not credited before the superhero days. However, it is well known that Stan Lee (sometimes assisted by Larry Lieber, or Lieber on his own) wrote the overwhelming majority of these stories from 1959 to 1963. Where there is no positive confirmation, credits may be listed as "Stan Lee ?; Larry Lieber ?", or either person individually, or simply "?", according to the indexer's best information.